A high-temperature heat protection material thermal conductivity testing device

Abstract

The present application relates to a kind of high-temperature heat protection material thermal conductivity testing device, belong to heat protection material thermal conductivity testing technical field, solve the problem that the test temperature range is not enough in prior art, test upper limit is too low, cannot accurately and efficiently test the high-temperature thermal conductivity of certain aircraft heat protection material.Testing device includes gas tunnel test section and the gas tunnel nozzle section for being used to the high-temperature gas of gas tunnel test section injection;Gas tunnel test section is installed with heat insulation device, heat insulation device is the cavity structure of one end opening, opening side is opposite with the nozzle of gas tunnel nozzle section, and the sample to be measured is placed in the cavity of heat insulation device;Heat flow meter and temperature sensor are arranged in three regions, inner layer is used for testing data to calculate, middle and outer layer is used for monitoring device heat loss condition.The testing device of the present application realizes the thermal conductivity in-situ test by gas tunnel heating energy reproduction heat protection material actual use condition, with the advantages of large test range, high test upper limit, precision etc..

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of physical property testing of thermal protection materials, and particularly relates to a high-temperature thermal protection material thermal conductivity testing device. BACKGROUND

[0002] With the rapid development of aerospace, especially hypersonic flight, a series of technical problems need to be solved, and the thermal barrier is the first problem to be solved in the development of hypersonic vehicles. When the vehicle flies at high speed in the atmosphere, it collides and rubs with the air to produce extremely high temperature, so that the hypersonic vehicle is in an extremely harsh aerodynamic heating environment, and the thermal protection material is also required to have good high-temperature performance to adapt to the harsh aerodynamic heating environment.

[0003] Thermal conductivity is a crucial parameter for thermal protection materials. Thermal conductivity of thermal protection materials is a parameter representing the size of the thermal conductivity of thermal protection materials, that is, the amount of heat per unit area per unit time when the temperature decreases by one degree per unit length in the direction of heat transfer. The thermal conductivity testing technology is based on the one-dimensional steady-state Fourier heat transfer law. A sample with a certain width-to-thickness ratio is placed between the heating device and the cooling device. When the temperature of the hot surface of the sample to be tested and the temperature of the cold surface of the sample to be tested are uniformly and constantly at a certain temperature difference, the ideal state will establish a quasi-one-dimensional longitudinal steady-state heat flow in the interior (especially the central region). According to the heat flux density, the hot surface temperature of the sample to be tested, the cold surface temperature of the sample to be tested and the thickness of the sample to be tested, the thermal conductivity of the sample to be tested can be obtained.

[0004] The heating device is the main body of the whole thermal conductivity testing device. The upper limit of the heating of the steady-state thermal protection material thermal conductivity testing device is 1000K, which is far from the actual working temperature of the thermal protection material of the hypersonic vehicle. The energy pulse of the transient laser testing device can reach 2700K, but the transient laser testing device is only suitable for testing high thermal conductivity materials such as metals, graphite, graphene and silicon carbide, and cannot test the multi-layer composite material of the thermal protection material of the vehicle with extremely low thermal conductivity. The actual working temperature of the high-temperature thermal protection material of the hypersonic vehicle can be as high as 3000K, and the thermal conductivity of the material is extremely low. The thermal conductivity of the material and the temperature show a nonlinear relationship. The existing thermal conductivity testing device cannot meet the testing requirements.

[0005] Therefore, in view of the limitations of the existing thermal protection material thermal conductivity testing device, it is urgent to provide a thermal conductivity in-situ testing device with a heating device of the testing device that can heat to the actual working temperature of the thermal protection material of the hypersonic vehicle, accurate and objective testing results, and high efficiency. SUMMARY

[0006] In view of the above analysis, the high-temperature thermal protection material thermal conductivity testing device is used to test the thermal conductivity of the aircraft thermal protection material with extremely high actual working temperature and extremely low thermal conductivity, so as to solve one or more of the problems of the existing testing device, the heating temperature of the heating device cannot reach the actual working temperature, the leakage of the device cannot be monitored, the test results are inaccurate, objective and inefficient.

[0007] In order to solve the above problems, the technical scheme adopted by the present application is as follows:

[0008] The application discloses a high-temperature thermal protection material thermal conductivity testing device, which comprises a gas tunnel test section and a gas tunnel nozzle section for spraying high-temperature gas to the gas tunnel test section.

[0009] A heat insulation device is installed in the gas tunnel test section, and the heat insulation device is a cavity structure with an open end, the open end is opposite to the nozzle of the gas tunnel nozzle section, and the sample to be measured is placed in the cavity of the heat insulation device.

[0010] Further, the cavity wall of the heat insulation device is a double-layer structure, the outer layer is a temperature control layer, the inner layer is an insulation layer, and the shapes of the outer layer and the inner layer are matched.

[0011] Further, a temperature control medium circulating pipeline is arranged in the temperature control layer, and a pipeline inlet end and a pipeline outlet end are arranged on the outer surface of the temperature control layer.

[0012] Further, along the direction from the bottom of the cavity of the heat insulation device to the open end, a constant temperature cold plate, a sample mounting plate and a sample to be measured are sequentially arranged in the heat insulation device, and the sizes of the three are matched, the surface of the constant temperature cold plate and the surface of the sample mounting plate are parallel to the hot surface of the sample to be measured, and the high-temperature gas is sprayed to the sample to be measured along the direction from the open end of the heat insulation device to the bottom of the cavity.

[0013] Further, a heat flow meter mounting groove for mounting a heat flow meter and a temperature sensor mounting groove for mounting a temperature sensor are arranged on the constant temperature cold plate, and the number of the heat flow meter and the temperature sensor is multiple.

[0014] Further, the sample mounting plate comprises an inner layer region, a middle layer region and an outer layer region in sequence along the direction away from the center; a rectangular coordinate system is established with the geometric center of the sample mounting plate as the origin, the horizontal direction is the x direction, and the vertical direction is the y direction.

[0015] The vertex coordinates of the inner area are (2a, 2a), (2a, -2a), (-2a, -2a), (-2a, 2a); the vertex coordinates of the middle area are (4a, 4a), (4a, -4a), (-4a, -4a), (-4a, 4a); the vertex coordinates of the outer area are (6a, 6a), (6a, -6a), (-6a, -6a), (-6a, 6a); a is the unit length.

[0016] Furthermore, the above-mentioned sample mounting plate is composed of inner layer plates, middle layer plates and outer layer plates that are concentrically nested from the inside to the outside. The interval between adjacent plates of the inner layer plates, middle layer plates and outer layer plates is 1 mm, and the inner layer area, middle layer area and outer layer area correspond to the areas where the inner layer plates, middle layer plates and outer layer plates are located in turn.

[0017] Furthermore, the heat flux meter and temperature sensor installed on the above-mentioned constant temperature cold plate are set in different areas, and the test data value points of the cold surface of the sample to be tested are set in different areas. The area settings of the constant temperature cold plate and the sample to be tested are both realized through the area settings of the sample mounting plate.

[0018] Furthermore, the number of the heat flow meters is 3 and the number of the temperature sensors is 12;

[0019] With the geometric center of the constant temperature cold plate surface as the origin, a rectangular coordinate system is established on the surface of the constant temperature cold plate, with the horizontal direction being the x direction and the vertical direction being the y direction;

[0020] The installation position coordinates of the above heat flow meter are (0, 0), (0, -3a), and (0, -5a), where a is the unit length;

[0021] The installation position coordinates of the above-mentioned temperature sensors are (a, 0), (0, a), (-a, 0), (0, -a), (3a, 0), (0, 3a), (-3a, 0), (0, -3a), (5a, 0), (0, 5a), (-5a, 0) and (0, -5a), where a is the unit length.

[0022] Furthermore, the test results of the heat flow meter and temperature sensor in the inner layer area are used to calculate the thermal conductivity, and the heat flow meter and temperature sensor in the middle and outer layer areas are used to monitor the heat leakage of the test device.

[0023] The present invention can achieve at least one of the following beneficial effects:

[0024] 1. The high-temperature thermal protection material thermal conductivity testing device provided by the application can heat the sample to be tested by a gas wind tunnel, so that the surface temperature of the sample to be tested reaches the actual surface temperature of a hypersonic aircraft during hypersonic flight, such as 3000K, which is closer to the actual working condition, and compared with the prior art, the testing device has an improved upper limit of testing, an expanded testing range, and provides an objective prerequisite for the accuracy of the testing results.

[0025] 2. The high-temperature thermal protection material thermal conductivity testing device provided by the application adopts a cavity structure for the heat insulation device of the test section, and the cavity wall has a double-layer structure, so that heat loss of the testing area can be effectively avoided, the sample to be tested can be effectively maintained in one-dimensional heat transfer, and among the heat flow meters and temperature sensors in the inner, middle and outer regions, only the heat flow meter and temperature sensor in the inner region are used for calculating the thermal conductivity, and the heat flow meters and temperature sensors in the middle and outer regions are used for monitoring the heat leakage of the testing device and the direction of heat leakage, so that the testing results are more accurate, and the testing efficiency is greatly improved.

[0026] 3. The application can test the thermal conductivity of environmental materials above 3000 DEG C, but the prior art cannot test block thermal protection materials above 1500 DEG C at present, and the preferred embodiments and comparative examples only test the fiber-woven reinforced phenolic resin-based thermal protection material with a known thermal conductivity of 0.12 at 1000 DEG C and 2700 DEG C, and according to the results of the embodiments and comparative examples, the thermal conductivity testing by using the testing device of the application has a result error of less than 0.01, which is 0.03 lower than that of the conventional testing method, and the accuracy of testing is improved.

[0027] In the application, the above technical solutions can be combined with each other to realize more preferred combination solutions. Other features and advantages of the application will be described in the subsequent specification, and some advantages will become apparent from the specification or be understood by implementing the application. The purposes and other advantages of the application can be realized and obtained from the contents specifically indicated in the specification and the drawings. BRIEF DESCRIPTION OF DRAWINGS

[0028] The accompanying drawings are included to provide a further understanding of the application and are incorporated herein and constitute a part of the application. The drawings illustrate embodiments of the application and, together with the description, serve to explain the principles of the application.

[0029] Figure 1 It is a structure front view of the high-temperature thermal protection material thermal conductivity testing device of the application.

[0030] Figure 2 It is a structure sectional view of the heat insulation device in the thermal conductivity testing device provided by the embodiment of the application.

[0031] Figure 3 It is a structure sectional view of the heat insulation device in the thermal conductivity testing device provided by the embodiment of the application.Figure 1 The right side view of the structure of the sample mounting plate;

[0032] Figure 4 for Figure 1 The right side view of the structure on the constant temperature cold plate shows the layout of the heat flux meter and temperature sensor on the constant temperature cold plate;

[0033] Figure 5 It is a three-dimensional diagram of the thermal insulation device of the present invention.

[0034] Reference numerals:

[0035] 1-Gas wind tunnel test section; 2-Gas wind tunnel nozzle; 3-Infrared thermometer; 4-Thermal insulation device; 41-Cooling layer; 42-Circulating water circuit; 43-Anchor installation; 44-Thermal insulation layer; 45-Water inlet interface; 46-Wire threading hole; 47-Water outlet interface; 5-Constant temperature cold plate; 51-Sensor threading hole; 52-First heat flux meter (inner layer); 53-Second heat flux meter (middle layer); 54-Third heat flux meter (outer layer); 55-Outer layer temperature sensor; 56-Middle layer temperature sensor; 57-Inner layer temperature sensor; 6-Sample mounting plate; 61-Sample mounting plate outer layer; 62-Sample mounting plate middle layer; 63-Sample mounting plate inner layer; 64-Ceramic clip; 7-Sample to be tested; 8-Constant temperature water chiller; 9-Data acquisition system; 10-Computer; 11-Circulating water chiller. DETAILED DESCRIPTION

[0036] The preferred embodiments of the present invention will be described in detail below in conjunction with the accompanying drawings, wherein the accompanying drawings constitute a part of this application and are used together with the embodiments of the present invention to illustrate the principles of the present invention, and are not used to limit the scope of the present invention.

[0037] The actual operating temperature of high-temperature thermal protection materials for hypersonic aircraft can reach up to 3000K, and their thermal conductivity is extremely low. The thermal conductivity of the material shows a nonlinear relationship with temperature. The current existing thermal conductivity testing equipment is far from meeting its testing needs.

[0038] A specific embodiment of the present invention discloses a device for testing the thermal conductivity of high-temperature thermal protection materials. Figure 1 As shown, the testing device for the thermal conductivity of high-temperature heat protection materials of the present invention includes: a gas wind tunnel test section 1 and a gas wind tunnel nozzle section 2 for spraying high-temperature gas into the gas wind tunnel test section.

[0039] Compared with the prior art, the high-temperature gas generated by the gas wind tunnel is directly used to heat the thermal protection material to be tested, so that the hot surface temperature of the thermal protection material to be tested reaches the high temperature in the actual working condition, the heating temperature of the gas wind tunnel can be as high as 3000K, and the actual working condition temperature of the thermal protection material of the hypersonic aircraft can be reached. For this temperature, the existing thermal conductivity test method cannot meet the test requirements, therefore, the application can break through the limitations of the current thermal conductivity test method of thermal protection materials, and can realize the thermal conductivity test of the multilayer composite material such as the thermal protection material of the aircraft, which has high actual working condition temperature and extremely low thermal conductivity.

[0040] It should be noted that the high-temperature wind tunnel includes a gas wind tunnel, an arc wind tunnel and a shock wave wind tunnel, all of which have the function of generating high-temperature hot gas, and the temperature can reach 3000K, which is close to the actual working condition temperature of the hypersonic aircraft. However, experiments show that the arc wind tunnel and the shock wave wind tunnel will produce electromagnetic interference, which will affect the accuracy of the test device, therefore, the gas wind tunnel is used as a heating device, and the high-temperature hot gas generated by the gas wind tunnel is used to heat the sample to be tested, which is more beneficial to the accuracy and reliability of the test results.

[0041] As shown in Figure 2 , the heat insulation device 4 is installed in the test section 1 of the gas wind tunnel, the heat insulation device is a cavity structure with one end open (as shown in Figure 5 ), the opening side is opposite to the nozzle of the nozzle section of the gas wind tunnel, along the direction from the bottom of the cavity to the opening side, the heat insulation device is provided with a constant temperature cold plate 5, a sample mounting plate 6 and a sample to be tested 7 from inside to outside, the surface of the constant temperature cold plate, the surface of the sample mounting plate and the high-temperature gas injection surface of the sample to be tested are parallel and have the same size, and the high-temperature gas is injected to the sample to be tested along the direction from the opening side of the heat insulation device to the bottom of the cavity.

[0042] The thermal conductivity test technology is based on the one-dimensional steady-state Fourier heat transfer law as the theoretical basis, and is based on one-dimensional heat transfer, which allows heat to be transferred along a straight line. However, in fact, one-dimensional heat transfer is an ideal state, and it is necessary to avoid heat loss as much as possible to test accurate data. The cavity structure and the double-layer structure of the cavity wall of the heat insulation device of the application effectively maintain one-dimensional heat conduction.

[0043] Specifically, the high-temperature hot gas generated by the gas wind tunnel can be as high as 3000K, and the hot surface temperature of the sample to be tested heated by the gas wind tunnel can be as high as 1000℃ or above. However, the internal test elements of the test section need to operate normally, and need to be ensured below 200℃, therefore, the heat insulation device needs to be set to protect the test elements, and further, the heat insulation device is set to a cavity structure, and the constant temperature cold plate, the sample mounting plate and the sample to be tested are wrapped therein to protect the test elements from high temperature damage.

[0044] The internal temperature of the heat insulation device is within 200°C, and the external temperature is above 1000°C. If a single layer of thermal protection is used, the temperature difference between the inside and outside is nearly 1000°C, which is difficult to ensure the stability of the test device. Therefore, a double or multi-layer structure is needed. Further, as shown in Figure 2 , a double water-cooling structure is used, and the internal temperature and the water-cooling layer temperature are controlled within 200°C, which effectively reduces the influence of the environment on the sample to be tested. Further, the inner layer structure 44 is a heat preservation layer made of heat insulation material, which has extremely low thermal conductivity, thereby reducing the heat transfer between the inside and outside of the heat insulation device. The outer layer structure 41 is a metal shell made of stainless steel or other metal materials with water-cooling function, which is filled with a circulating water path 42, and the water inlet and outlet interfaces 45 and 46 are connected to the circulating water cooler 11 to provide circulating water cooling for the heat insulation device. Through the design of inner heat preservation and outer water cooling, the environmental temperature in the heat insulation device is not affected or less affected by the external environmental temperature, thereby ensuring the objectivity of the test results of the test element.

[0045] In order to make the test results accurate, the cold surface temperature of the sample to be tested needs to be controlled, which is achieved by controlling the temperature of the constant temperature cold plate. Specifically, as shown in Figure 4 , the constant temperature cold plate has a circulating water path inside, which is connected to a constant temperature water cooler to ensure that the temperature of the constant temperature cold plate is maintained within a certain range. Further, the temperature sensor and the heat flow meter are the best choices for installation on the constant temperature cold plate. In order to make the surface of the constant temperature cold plate flat and better contact the sample to be tested, a groove can be provided for installing the temperature sensor (55, 56, 57) and the heat flow meter (52, 53, 54). In this way, the temperature sensor contacts the cold surface of the sample to be tested for testing the temperature reached by the cold surface of the sample after heating; and the heat flow meter is used to test the heat flux injected into the sample to be tested.

[0046] It should be noted that the thermal conductivity of the sample to be tested is extremely low, and it is difficult to accurately measure the surface of the temperature sensor and the heat flow meter. After repeated experiments, a high thermal conductivity metal material can be provided as a test medium between the constant temperature cold plate and the sample to be tested. Exemplarily, the high thermal conductivity metal material is designed in the form of a thin plate, which is tightly attached to the cold surface of the sample to be tested to ensure that the cold surface temperature is quickly and accurately transmitted to the metal plate. The high thermal conductivity metal plate needs to satisfy the thermal conductivity ≥ 16.3 W·m -1 ·K -1 . Exemplarily, such as a stainless steel plate. Since this high thermal conductivity metal plate is next to the sample, it is referred to as a sample mounting plate below.

[0047] In order to make the test data more accurate and ensure that the heat is transmitted in a straight line, in one possible design, the heat dissipation condition of the monitoring test device is tested by setting the sample to be tested in the inner, middle and outer three layers.

[0048] Since the metal plate has high thermal conductivity, if a whole metal plate is used as the sample mounting plate, under the high-temperature gas jet, the heat is transferred very quickly, the temperature difference between the regions of the sample mounting plate disappears instantaneously, the whole plate reaches a consistent temperature very quickly, and the temperature of each region of the inner, middle and outer layers cannot be distinguished, so that the uniformity of the temperature of each region and whether there is heat leakage cannot be accurately judged.

[0049] In order to facilitate the detection of heat leakage, the sample mounting plate is specially designed, and specifically, as shown in Figure 3 , the sample mounting plate is nested and spliced from the inner to the outer by three plates with a thickness of 2 mm, the inner layer plate 63 is a solid plate, and the middle layer plate 62 and the outer layer plate 61 are frame-shaped and correspond to the inner, middle and outer layers of the sample of the heat protection material to be tested. When spliced, there is a gap, such as 1 mm, between the inner layer plate, the middle layer plate and the outer layer plate, and the inner layer plate, the middle layer plate and the outer layer plate are sequentially fixedly connected through connecting points. After splicing, the three plates form a complete sample mounting plate. Exemplarily, the connecting point fixation of each layer can be fixed by four ceramic buckles 64. Specifically, in order to ensure the flatness of the surface of the sample mounting plate, ceramic buckles are installed on the sample mounting plate through grooves; the ceramic buckles have high hardness and low thermal conductivity, and can not only connect the three metal plates into a whole sample mounting plate, but also reduce the heat transfer of different regions.

[0050] It should be emphasized that the inner, middle and outer layer partitions of the sample mounting plate realize the partition of the constant-temperature cold plate and the sample of the heat protection material to be tested. This is because the constant-temperature cold plate surface, the sample mounting plate surface and the hot surface of the sample of the heat protection material to be tested are parallel and have the same size matching, so that the inner, middle and outer layer partition of the constant-temperature cold plate and the inner, middle and outer layer partition test of the sample of the heat protection material to be tested can be realized by the partition on the sample mounting plate.

[0051] The constant-temperature cold plate surface, the sample mounting plate surface and the hot surface of the sample of the heat protection material to be tested are parallel and have the same size matching, and the parameters of the coordinates are as follows:

[0052] As shown in Figure 3 , a rectangular coordinate system is established on the upper surface of the sample mounting plate with the geometric center of the surface of the sample mounting plate as the origin, the horizontal direction is the x direction, and the vertical direction is the y direction. The sample mounting plate is divided into three regions of the inner, middle and outer layers, the vertex coordinates of the inner layer region are (2a, 2a), (2a, -2a), (-2a, -2a) and (-2a, 2a) respectively; the vertex coordinates of the middle layer region are (4a, 4a), (4a, -4a), (-4a, -4a) and (-4a, 4a) respectively; the vertex coordinates of the outer layer region are (6a, 6a), (6a, -6a), (-6a, -6a) and (-6a, 6a) respectively; a is a unit length.

[0053] As shown in Figure 4As shown, a rectangular coordinate system is established on the upper surface of the constant temperature cold plate with the geometric center of the constant temperature cold plate surface as the origin, the horizontal direction as the x direction, and the vertical direction as the y direction. The heat flow meters and temperature sensors of the inner, middle and outer three regions installed on the constant temperature cold plate are as follows: the coordinates of the installation positions of the three heat flow meters are (0, 0), (0, -3a) and (0, -5a) respectively; the coordinates of the installation positions of the twelve temperature sensors are (a, 0), (0, a), (-a, 0), (0, -a), (3a, 0), (0, 3a), (-3a, 0), (0, -3a), (5a, 0), (0, 5a), (-5a, 0) and (0, -5a) respectively, and a is a unit length.

[0054] The partition design of the sample mounting plate provides more intuitive conditions for the implementation of the value partition of the test results of the to-be-tested sample. The to-be-tested sample is tested in the inner, middle and outer three layers, and the purpose is to test the degree of deviation from one dimension of the test, that is, the quality of the test results, so that the test data is more accurate. Therefore, among the heat flow meters and temperature sensors of the inner, middle and outer three regions installed on the constant temperature cold plate, only the heat flow meters and temperature sensors in the inner region are used for calculating the thermal conductivity, and the heat flow meters and temperature sensors in the middle and outer regions are used for monitoring the heat leakage of the test device and the direction of the heat leakage.

[0055] Specifically, the inner, middle and outer three regions of the cold surface of the to-be-tested heat protection material sample are each tested once for the heat flux density value and four times for the temperature value, and three heat flux density values and twelve temperature values are measured respectively.

[0056] The coordinates of the three heat flux density values and positions are q1(0, 0), q2(0, -3a) and q3(0, -5a) respectively, and a is a unit length.

[0057] The coordinates of the twelve temperature values and positions are (a, 0), (0, a), (-a, 0), (0, -a), (3a, 0), (0, 3a), (-3a, 0), (0, -3a), (5a, 0), (0, 5a), (-5a, 0) and (0, -5a) respectively, and a is a unit length.

[0058] Specifically, the heat flux density values and temperature values of the above-mentioned inner, middle and outer three regions are only the heat flux density values and temperature values in the inner layer region for testing and calculating the thermal conductivity, and the heat flux density values and temperature values in the middle and outer layers are used for monitoring the heat leakage of the test system through data.

[0059] Specifically, the heat flux density value q1 of the inner layer region of the sample cold surface is measured, and the coordinate is (0, 0); the temperature values t 1-1 , t 1-2 , t 1-3 , t 1-4corresponding to the coordinates (3a, 0), (0, 3a), (-3a, 0), (0, -3a), (5a, 0), (0, 5a), (-5a, 0) and (0, -5a), a being a unit length.

[0060] measured other temperature values t 2-1 , t 2-2 , t 2-3 , t2-4, t 3-1 , t 3-2 , t 3-3 , t 3-4 corresponding to the coordinates (3a, 0), (0, 3a), (-3a, 0), (0, -3a), (5a, 0), (0, 5a), (-5a, 0) and (0, -5a), a being a unit length.

[0061] More specifically, the middle layer heat flow meter is used to measure the heat flux density value q2 passing through the middle layer of the cold surface of the sample under test, and the temperature sensor of the middle layer is used to test the middle layer temperature t2 of the cold surface of the sample under test 2-1 , t 2-2 , t 2-3 , t 2-4 ; the outer layer heat flow meter is used to measure the heat flux density value q2 passing through the outer layer of the cold surface of the sample under test, and the temperature sensor of the outer layer is used to test the outer layer temperature t2 of the cold surface of the sample under test 3-1 , t 3-2 , t 3-3 , t 3-4 The heat flow meters and temperature sensors of the middle layer and outer layer regions are used to monitor the heat leakage of the test device and the direction of the heat leakage.

[0062] More specifically, when the inner layer temperature value is greater than the outer layer value, and the difference between the maximum temperature value and the minimum temperature value of the temperature sensor (i.e. t max -t min ) is greater than 5% of the average temperature, it indicates that there is heat leakage in the heat insulation device, and then the direction of the heat leakage is determined according to the minimum value (t min ) of the temperature sensor; similarly, if the heat flux density value difference is within a certain range, that is, the difference between the maximum heat flux density value and the minimum heat flux density value, i.e. q max -q min is less than 3% of q1, it indicates that the heat loss in the sample under test is less and close to one-dimensional heat transfer, and if the heat flux density value difference is greater, i.e. q max -q min is greater than 3% of q1, it indicates that there is heat leakage in the heat insulation device; the test is stopped when heat leakage is found, the heat insulation material at the heat leakage position is replaced, and the sample under test is adjusted and then the test is continued.

[0063] Specifically, the test process includes:

[0064] Step 1, install the gas wind tunnel test section 1 and the gas wind tunnel nozzle section 2.

[0065] Specifically, if Figure 1 As shown, the heat insulation device with a bracket is fixed to the gas wind tunnel test section 1 through the foot 43, and the opening end of the heat insulation device 4 is completely open to place the constant temperature cold plate 5, the sample mounting plate 6 and the sample to be tested 7; Figure 2 As shown, the tail end is provided with a water inlet interface 45 and a water outlet interface 47, which are connected to the circulating water chiller 11; a threading hole 46 is provided at the center of the tail end, and the cooling pipes of the constant temperature cold plate 5 and the heat flow meter and temperature sensor leads in the test device pass through these two threading holes 46;

[0066] The constant temperature cold plate is close to the inner wall of the insulation device and is provided with an inlet and outlet water cooling pipe, which can pass through the threading hole 46 at the rear of the insulation device and connect to the constant temperature water cooler 8; the other side is in contact with the sample mounting plate 6, such as Figure 4 As shown, there are slots for installing temperature sensors 55, 56, 57 and heat flow meters 52, 53, 54. The leads of the temperature sensors and heat flow meters pass through the wire holes 51 reserved in the constant temperature cold plate and then pass through the wire holes 46 of the thermal insulation device.

[0067] Wrap the sensor leads and the water inlet and outlet pipes of the constant temperature cold plate with heat-insulating cotton felt, and seal the threading hole 26;

[0068] The sensor leads are connected to a data acquisition system 9, and the data acquisition system is connected to a computer 10;

[0069] Step 2: Process the sample 7 to be tested into a standard sample with a flat surface, a thickness of d, and length and width that match the dimensions of the constant temperature cold plate and the sample mounting plate;

[0070] Step 3: Place the heat flux meters 52, 53, 54 and the temperature sensors 55, 56, and 57 into the mounting grooves of the constant temperature cold plate 5 and apply thermal grease. Press and secure the sample mounting plate 6 to the constant temperature cold plate 5, ensuring that each of the inner, middle, and outer areas of the mounting plate is equipped with one heat flux meter and three temperature sensors.

[0071] Step 4: Bond the sample 7 to be tested to the sample mounting plate 6 with high-temperature resistant thermal conductive silicone rubber, with the position corresponding to the mounting plate; install the constant temperature cold plate 5, sample mounting plate 6, and sample 7 to be tested in sequence and place them in the thermal insulation device;

[0072] Step 5: Install the infrared thermometer 3 and align the measuring point with the center of the sample to be measured;

[0073] Step 6: Start the gas wind tunnel to heat the sample to be tested. When thermal equilibrium is reached, obtain the center temperature of the sample to be tested by the infrared thermometer as the hot surface temperature T, and obtain the temperature t of the four temperature sensors in the inner layer area. 1-1 , t 1-2 , t 1-3 , t 1-4, and inner layer heat flux density value q1

[0074] Step 7, obtaining the heat flux density values q2, q3 and temperature values t of the middle layer and the outer layer 2-1 , t 2-2 , t 2-3 , t 2-4 , t 3-1 , t 3-2 , t 3-3 , t 3-4 , for monitoring the heat loss of the test device;

[0075] Through analysis of the data obtained in steps 6 and 7, whether the heat flux density difference and the temperature difference meet the experimental requirements: the heat flux density difference is less than 5% of q1, and the maximum temperature difference is less than 5% of the average temperature; if the requirements are met, the test data in step 6 is valid, and the thermal conductivity can be calculated; if the requirements are not met, the lowest value (t min ) of the temperature sensor is used to determine the heat leakage direction, the heat insulation material at the heat leakage position is replaced, and the sample to be tested is adjusted and tested continuously until the experimental requirements are met.

[0076] Step 8, the center temperature T of the hot surface of the sample to be tested in step 6 that meets the experimental requirements, the thickness d of the sample to be tested, the inner layer heat flux q1 and the temperatures t 1-1 , t 1-2 , t 1-3 , t 1-4 of the four temperature sensors in the inner layer region are substituted into the following thermal conductivity calculation formula:

[0077]

[0078] Wherein, λ is the thermal conductivity of the material to be tested, the unit is W·m -1 ·K -1 ; d is the thickness of the sample to be tested, the unit is m; the thermal conductivity of the sample to be tested is calculated.

[0079] In the application, the sample to be tested is heated by using a gas wind tunnel, so that the hot surface temperature of the sample to be tested can reach the surface temperature of the actual hypersonic aircraft during hypersonic flight, such as 3000K, which is closer to the actual working condition, and provides an objective premise for the accuracy of the test data.

[0080] In the application, the heat insulation device adopts a cavity structure, and the cavity wall adopts a double-layer structure, which can effectively avoid heat loss in the test area, effectively maintain one-dimensional heat transfer of the sample to be tested, and ensure the accuracy of the test data.

[0081] The present application realizes the inner, middle and outer three-layer partition of the sample to be tested through the partition of the sample mounting plate, and only the thermal flow meter and temperature sensor test results of the inner layer area are used for calculating the thermal conductivity, and the thermal flow meter and temperature sensor of the middle layer and outer layer area are used for monitoring the heat leakage of the test device and the heat leakage position, so that the test data is ensured to be accurate, and the calculated thermal conductivity value is more accurate.

[0082] Embodiment 1

[0083] The embodiment of the present application discloses a high-temperature thermal protection material thermal conductivity testing device, which comprises: Figure 1 As shown in the figure, a gas tunnel test section 1 and a gas tunnel nozzle section 2 for injecting high-temperature gas into the gas tunnel test section;

[0084] A heat insulation device 4 is installed in the gas tunnel test section, which is a cavity structure with one end open, and the opening side is opposite to the nozzle of the gas tunnel nozzle section, and the sample to be tested is placed in the cavity of the heat insulation device.

[0085] Specifically, as shown in the figure, Figure 2 The heat insulation device 4 with a support is fixed in the gas tunnel test section 1 through a foot 43, the open end of the heat insulation device 4 is completely open, and is used for placing a constant temperature cold plate 5, a sample mounting plate 6 and a sample to be tested 7; the cavity wall of the heat insulation device is a double-layer structure, the inner layer is an insulation layer 44 made of heat insulation materials such as ceramic fiber and the like, and the outer layer is a cooling layer 41 such as a metal water cooling layer, which is an outer shell made of metal materials such as stainless steel and having a water cooling function, and a circulating water channel 42 is arranged inside; a water inlet interface 45 and a water outlet interface 47 are arranged at the tail end and are connected with a circulating water cooler 11; a threading hole 46 is arranged at the center position of the tail end, and the cooling pipe of the constant temperature cold plate 5 and the lead wires of the thermal flow meter and temperature sensor in the test device pass through the two threading holes 46;

[0086] Specifically, as shown in the figure, Figure 4 The constant temperature cold plate is provided with inlet and outlet water cooling pipes on one side of the inner wall of the heat insulation device, can pass out from the threading hole 46 at the rear part of the heat insulation device, and is connected with a constant temperature water cooler 8; the other side is in contact with the sample mounting plate 6 and is provided with a slot for mounting temperature sensors 55, 56 and 57 and thermal flow meters 52, 53 and 54, and the lead wires of the temperature sensors and thermal flow meters pass out through the threading hole 51 reserved in the constant temperature cold plate and then pass out through the threading hole 46 of the heat insulation device;

[0087] As shown in the figure, Figure 3As shown, the sample mounting plate is nested and spliced from three 2mm-thick plates from the inside out. The inner layer plate 63 is solid plate-shaped, and the middle layer plate 62 and the outer layer plate 61 are frame-shaped, corresponding to the inner, middle and outer layers of the thermal protection material sample to be tested. When assembled, there is a 1mm gap between the inner, middle and outer layer plates, and the inner, middle and outer layer plates are sequentially fixed and connected by four ceramic buckles 64. After assembly, the three plates form a complete sample mounting plate.

[0088] The sensor lead and the inlet and outlet pipes of the constant temperature cold plate are wrapped with thermal insulation cotton felt, and the threading hole 26 is sealed;

[0089] The sensor lead is connected to the data acquisition system 9, and the data acquisition system is connected to the computer 10.

[0090] Example 2

[0091] A fiber-woven reinforced phenolic resin-based thermal protection material (aircraft thermal protection material) with a known thermal conductivity of 0.12 W / (m·K) was tested for thermal conductivity at 2700°C, including the following steps:

[0092] Step 1, install the gas tunnel test section and the gas tunnel nozzle section;

[0093] Specifically, the heat insulation device with a bracket is fixed to the gas tunnel test section by the foot, and the opening end of the heat insulation device is completely open for placing the constant temperature cold plate, sample mounting plate and thermal protection material sample to be tested; The tail end is provided with two threading holes for the cooling pipe of the constant temperature cold plate and the heat flow meter and temperature sensor lead in the test device to pass through the two threading holes;

[0094] One side of the constant temperature cold plate is provided with cooling pipe inlet and outlet pipes, which can be passed out of the threading hole at the rear of the heat insulation device and connected to the constant temperature water cooler. The other side is in contact with the sample mounting plate and is provided with a slot for installing the temperature sensor and the heat flow meter. The temperature sensor and the heat flow meter lead are passed out of the threading hole reserved in the constant temperature cold plate, and then out of the threading hole in the heat insulation device;

[0095] The sensor lead and the inlet and outlet pipes of the constant temperature cold plate are wrapped with thermal insulation cotton felt, and the threading hole is sealed;

[0096] The sensor lead is connected to the data acquisition system and the computer.

[0097] Step 2, process the thermal protection material sample to be tested into a standard thermal protection material sample with a thickness d=20mm, a length and width of 100mm, matching the size of the constant temperature cold plate and the sample mounting plate;

[0098] Step 3, put the heat flow meter and temperature sensor into the installation slot of the constant temperature cold plate, coat with thermal conductive silicone grease (thermal conductivity of 12 w / (m·K) or more), press and fix the mounting plate and the constant temperature cold plate, ensure that the inner, middle and outer three areas of the mounting plate are each provided with one heat flow meter and four temperature sensors for testing the cold surface temperature value and heat flux density value of each area of the sample of the heat protection material to be tested;

[0099] Step 4, adhere the sample of the heat protection material to be tested to the sample mounting plate with high-temperature resistant thermal conductive adhesive, and the position corresponds to the mounting plate; sequentially install the constant temperature cold plate, sample mounting plate and sample of the heat protection material to be tested, and place them into the heat insulation device;

[0100] Step 5, install the infrared temperature measuring instrument, and align the measuring point with the center of the sample of the heat protection material to be tested;

[0101] Step 6, start the gas wind tunnel to heat the sample of the heat protection material to be tested, when the heat balance is reached, obtain the center temperature of the sample of the heat protection material to be tested tested by the infrared temperature measuring instrument as the hot surface temperature T = 2705.3℃, and obtain the temperatures t 1-1 = 84.9℃, t 1-2 = 84.5℃, t 1-3 = 84.8℃, t 1-4 = 84.5℃ and the inner layer heat flux density value q1 = 17033.9W / m 2 ;

[0102] Step 7, obtain the heat flux density values q2 = 17003.5W / m 2 , q3 = 16909.8W / m 2 and the temperature values t 2-1 = 82.6℃, t 2-2 = 82.3℃, t 2-3 = 82.4℃, t 2-4 = 82.4℃, t 3-1 = 81.4℃, t 3-2 = 81.2℃, t 3-3 = 81.5℃, t 3-4 = 81.6℃, for monitoring the heat loss of the test device;

[0103] Through analysis of the data obtained in steps 6 and 7, the heat flux density difference and the temperature difference meet the experimental requirements: the heat flux density difference is 124.1W / m 2 , which is less than 5% of q1, the temperature uniformity is good, the maximum temperature difference is 3.7℃, which is less than 5% of the average temperature of the inner layer, and the test data in step 6 is effective, and the heat rate can be calculated;

[0104] Step 8, the measured sample hot face center temperature T, the sample thickness d, the inner layer heat flux q1 and the temperature t of the four temperature sensors in the inner layer region 1-1 1-2 1-3 1-4 Substitute the following thermal conductivity calculation formula:

[0105]

[0106] The thermal conductivity of the measured sample is 0.13 W / (m·K);

[0107] Compared with the known thermal conductivity of 0.12 W / (m·K), the error is less than 1%.

[0108] Example 3

[0109] The thermal conductivity of the fiber woven reinforced phenolic resin-based thermal protection material with a known thermal conductivity of 0.12 W / (m·K) was tested at 1000℃, including the following steps:

[0110] Step 1, install the gas tunnel test section and the gas tunnel nozzle section;

[0111] Specifically, the heat insulation device with a bracket is fixed to the gas tunnel test section through the foot, and the opening end of the heat insulation device is completely open for placing the constant temperature cold plate, sample mounting plate and measured sample; the tail end is provided with two threading holes for the cooling pipe of the constant temperature cold plate and the heat flow meter and temperature sensor lead wires in the test device to pass through the two threading holes;

[0112] The constant temperature cold plate is provided with water inlet and outlet pipes on one side, which can pass out of the threading hole at the rear of the heat insulation device and be connected to the constant temperature water cooler. The other side is in contact with the sample mounting plate and is provided with a slot for installing temperature sensors and heat flow meters. The temperature sensor and heat flow meter lead wires pass out of the threading hole reserved in the constant temperature cold plate and then pass out of the threading hole in the heat insulation device;

[0113] Wrap the sensor lead wires and the constant temperature cold plate water inlet and outlet pipes with heat insulation cotton felt, and plug the threading holes;

[0114] Connect the sensor lead wires to the data acquisition system and computer;

[0115] Step 2, process the measured sample into a standard measured sample with a flat surface, a thickness d of 20 mm, and a length and width of 100 mm, which matches the size of the constant temperature cold plate and sample mounting plate;

[0116] ​​​Step 3, put the heat flow meter and temperature sensor into the installation slot of the constant temperature cold plate, coat with thermal conductive silicone grease (thermal conductivity of 12 w / (m·K) or more), press and fix the installation plate and the constant temperature cold plate, and ensure that the inner, middle and outer three layers of the installation plate are each provided with one heat flow meter and four temperature sensors;

[0117] Step 4, bond the sample to be tested to the sample installation plate with high-temperature-resistant thermal conductive silicone rubber, and the position corresponds to the installation plate; install the constant temperature cold plate, sample installation plate and sample to be tested in sequence, and put them into the heat insulation device;

[0118] Step 5, install the infrared temperature measuring instrument, and align the measuring point with the center of the sample to be tested;

[0119] Step 6, start the gas wind tunnel to heat the sample to be tested, when the heat balance is reached, obtain the center temperature of the sample to be tested as the hot surface temperature T = 1003.6℃, and obtain the temperatures t 1-1 = 45.6℃, t 1-2 = 45.3℃, t 1-3 = 45.8℃, t 1-4 = 45.4℃ and the inner layer heat flux value q1 = 6228.3W / m 2 ;

[0120] Step 7, obtain the heat flux values q2 = 6223.2W / m 2 , q3 = 6222.6W / m 2 and the temperature values t 2-1 = 45.3℃, t 2-2 = 45.1℃, t 2-3 = 45.4℃, t 2-4 = 45.1℃, t 3-1 = 44.5℃, t 3-2 = 44.1℃, t 3-3 = 44.6℃, t 3-4 = 44.2℃ of the middle and outer layers, which are used to monitor the heat loss of the test device;

[0121] Through analysis of the data obtained in steps 6 and 7, the heat flux difference and temperature difference meet the experimental requirements: the heat flux difference is less than 5% of q1, the temperature uniformity is good, the maximum temperature difference is 1.4℃, which is less than 5% of the average temperature, and the test data in step 6 is effective, so the thermal conductivity can be calculated;

[0122] Step 8, obtain the center temperature T of the sample to be tested, the thickness d of the sample to be tested, the inner layer heat flux q1 and the temperatures t 1-1 , t 1-2 , t 1-3 , t 1-4, the thermal conductivity calculation formula is as follows:

[0123]

[0124] The thermal conductivity of the measured sample is calculated as 0.13 W / (m·K).

[0125] Compared with the known thermal conductivity of 0.12 W / (m·K) of the material, the error is less than 0.01.

[0126] Comparative Example

[0127] The comparative example is also a fiber-woven reinforced phenolic resin-based thermal protection material (aircraft thermal protection material) with a known thermal conductivity of 0.12 W / (m·K), which is tested at 1000℃.

[0128] The upper limit of the test temperature of the heat flow meter method test device of a certain aerospace institute is 1000℃, there is no monitoring device for the heat leakage system, and the test data show that the thermal conductivity value is 0.09 W / (m·K).

[0129] Compared with the known thermal conductivity of 0.12 W / (m·K) of the material, the error is 0.03, which is much higher than the error of the embodiment of the present application.

[0130] The thermal conductivity test method of the high-temperature thermal protection material in the prior art is compared with the test results of the present application to evaluate the objectivity, accuracy and efficiency, etc., and to highlight the advantages and beneficial effects of the present application.

[0131] The above is only a preferred specific embodiment of the present application, but the protection scope of the present application is not limited thereto, any person skilled in the art can easily think of changes or replacements within the technical scope disclosed by the present application, which should be covered within the protection scope of the present application.

Claims

1. A thermal conductivity testing device for fiber braided reinforced phenolic resin-based high-temperature thermal protection materials, characterized in that: It includes a gas wind tunnel test section and a gas wind tunnel nozzle section for injecting high-temperature gas into the gas wind tunnel test section; A heat-insulating device is installed in the gas wind tunnel test section. The heat-insulating device is a cavity structure with one end open. The open side faces the nozzle of the gas wind tunnel nozzle section. The sample to be tested is placed in the cavity of the heat-insulating device. The cavity wall of the thermal insulation device is a double-layer structure, with the outer layer being a temperature control layer and the inner layer being a heat insulation layer, and the shapes of the outer layer and the inner layer matching each other; a temperature control medium circulation pipeline is provided in the temperature control layer, and a pipeline inlet end and a pipeline outlet end are provided on the outer surface of the temperature control layer; Along the direction from the bottom of the heat insulation device cavity to the open side, the heat insulation device is sequentially provided with a constant temperature cold plate, a sample mounting plate and a sample to be tested, and the dimensions of the three are matched, and the constant temperature cold plate surface and the sample mounting plate surface are parallel to the hot surface of the sample to be tested, and high temperature fuel gas is sprayed toward the sample to be tested along the direction from the open side of the heat insulation device to the bottom of the cavity; The sample mounting plate is composed of an inner plate, a middle plate, and an outer plate that are concentrically nested from the inside to the outside, wherein the inner layer area, the middle layer area, and the outer layer area correspond to the areas where the inner plate, the middle plate, and the outer plate are located in sequence; the inner plate is a solid plate, and the middle plate and the outer plate are frame-shaped; there are gaps between the inner plate, the middle plate, and the outer plate; The heat flux meters and temperature sensors installed on the constant temperature cold plate are arranged in different areas, and the test data sampling points of the cold surface of the sample to be tested are arranged in different areas. The test results of the heat flux meters and temperature sensors in the inner layer area are used to calculate the thermal conductivity, and the heat flux meters and temperature sensors in the middle and outer layers are used to monitor the heat leakage of the test device; The sample mounting plate includes an inner layer area, a middle layer area and an outer layer area in a direction away from the center; a rectangular coordinate system is established with the geometric center of the sample mounting plate as the origin, with the horizontal direction being the x direction and the vertical direction being the y direction; The vertex coordinates of the inner region are (2a, 2a), (2a, -2a), (-2a, -2a), (-2a, 2a); the vertex coordinates of the middle region are (4a, 4a), (4a, -4a), (-4a, -4a), (-4a, 4a); the vertex coordinates of the outer region are (6a, 6a), (6a, -6a), (-6a, -6a), (-6a, 6a); a is the unit length; The number of the heat flow meters is 3 and the number of the temperature sensors is 12; With the geometric center of the constant temperature cold plate surface as the origin, a rectangular coordinate system is established on the surface of the constant temperature cold plate, with the horizontal direction being the x direction and the vertical direction being the y direction; The installation position coordinates of the heat flow meter are (0, 0), (0, -3a), and (0, -5a), where a is a unit length; The installation position coordinates of the temperature sensor are (a, 0), (0, a), (-a, 0), (0, -a), (3a, 0), (0, 3a), (-3a, 0), (0, -3a), (5a, 0), (0, 5a), (-5a, 0) and (0, -5a), where a is a unit length; The differences between the heat flux density values ​​of the middle layer, the heat flux density values ​​of the outer layer, and the heat flux density values ​​of the inner layer are less than 5% of the heat flux density value of the inner layer; the maximum temperature differences between the temperatures of the four temperature sensors in the middle layer, the temperatures of the four temperature sensors in the outer layer, and the temperatures of the four temperature sensors in the inner layer are less than 5% of the average temperature of the inner layer; The error between the thermal conductivity of the tested sample and the known thermal conductivity of the material is less than 1%.

2. The thermal conductivity testing device for fiber braided reinforced phenolic resin-based high-temperature thermal protection materials according to claim 1, characterized in that: The constant temperature cold plate is provided with a heat flux meter installation slot for installing a heat flux meter and a temperature sensor installation slot for installing a temperature sensor, and the number of the heat flux meter and the number of the temperature sensor are both multiple.

3. The thermal conductivity testing device for fiber braided reinforced phenolic resin-based high-temperature thermal protection materials according to claim 2, characterized in that The spacing between adjacent inner, middle and outer layers is 1 mm.

4. The thermal conductivity testing device for fiber braided reinforced phenolic resin-based high-temperature thermal protection materials according to claim 3, characterized in that: The area settings of the constant temperature cold plate and the sample to be tested are both achieved through the area settings of the sample mounting plate.

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